1. Field of the Invention
The present invention relates to a series of image processing performed to print images taken with imaging devices, such as digital cameras.
2. Description of the Related Art
Printers commonly used in the field are capable of directly reading image data, which have been taken with an imaging device, such as a digital camera, and have been stored in a storage medium like a memory card, without a personal computer and printing images represented by the read image data. These common printers are also capable of directly reading image data from the imaging device, such as the digital camera, and printing images represented by the read image data. In the description below, the images taken with such an imaging device are referred to as ‘photo images’, and image data representing the photo images are referred to as ‘photo image data’. The printer that is capable of printing the photo images is called the ‘photo printer’.
The photo printer performs various image correction operations of the read photo image data as part of image processing required to ensure an adequate printing result of the photo image. The proposed image correction technique for correcting the photo image data is disclosed in, for example, Japanese Patent Laid-Open Gazette No. 2001-165647.
The photo printer requires preprocessing for the image correction. A typical procedure of preprocessing reads photo image data, samples pixel data from the read photo image data at a predetermined proportion to create a histogram, and performs a statistical process according to the created histogram to specify characteristic amounts representing the characteristics of the photo image and accordingly set correction parameters required for the image correction. The photo printer corrects the photo image data with the set correction parameters in the course of image processing executed for printing the photo image. The procedure of preprocessing may also perform a face recognition process to recognize the presence of any human face in the photo image and set the correction parameters required for the image correction. The procedure of preprocessing may further perform a red-eye reduction process to reduce the red-eye of the human face included in the photo image and set the correction parameters required for the image correction.
Such preprocessing is required for setting the correction parameters, prior to the required image correction and other required series of image processing for printing each photo image. When the user specifies a desired photo image for printing and gives a print start instruction, a certain time period is required for execution of the preprocessing before the actual start of the image processing of photo image data representing the specified photo image. Namely there is a relatively long wait time before start of the actual printing operation.
The photo image data are generally compressed in a specific compression format, for example, in a JPEG (Joint Photographic Coding Experts Group) format. Expansion of the photo image data compressed in the JPEG format is required before execution of the required image processing or the required preprocessing. This further extends the total wait time.